In recent years, the integration of patterns that are formed on a mask has become higher. Thus, to accurately transfer a fine pattern onto a wafer, a mask pattern must be illuminated with the optimal illuminance distribution. Accordingly, a technique that has drawn attention performs modified illumination at a pupil position of an illumination optical system for an exposure apparatus to form an annular-shaped or multipole-shaped (e.g., quadrupole) light intensity distribution and varies the light intensity distribution on a secondary light source, which is formed on a rear focal plane of a micro-fly's eye lens. This technique increases the focal depth and resolution of a projection optical system.
To transform light from a light source to light having an annular-shaped or multipole-shaped light intensity distribution at a pupil position, for example, Japanese Laid-Out Patent Publication No. 2002-353105 discloses an exposure apparatus including a movable multi-mirror (e.g., digital micromirror device (DMD), which includes many microscopic elements mirrors that are arranged in an array. The inclination angle and inclination direction of each of the element mirrors are varied to form a predetermined light intensity distribution at a pupil position of the illumination optical system or a position conjugated with the pupil position (secondary light source position formed at a rear focal plane of a micro-fly's eye lens). In this exposure apparatus, light entering each mirror element is reflected by a reflection surface of the mirror element, deflected by a predetermined angle in a predetermined direction, and transformed to light having a predetermined light intensity distribution at the pupil position of the illumination optical system. Exposure is performed by setting the inclination angle and inclination direction of each mirror element in the movable multi-mirror so that a secondary light source image formed on a rear focal plane of the micro-fly's eye lens has the optimal light intensity distribution that corresponds to the pattern or the like of the mask during exposure.